The invention relates to an adjusting device for a disk brake, in particular for a motor vehicle. The invention relates to a corresponding disk brake. The invention furthermore relates to a method for operating a wear adjustment device for a disk brake.
Vehicles and certain technical equipment often use friction brakes to convert kinetic energy. In this context, specifically in the passenger vehicle and commercial vehicle sector, disk brakes are preferred. With the typical design of a disk brake, the brake includes a brake caliper together with an internal mechanism, generally consisting of two brake linings and the brake disk. The cylinder forces are introduced into the internal mechanism via a pneumatically actuated cylinder, intensified by an eccentric mechanism and transmitted to the brake linings and brake disk as an application force via threaded spindles, where the wear of the brake disk and brake linings is compensated by the threaded spindles.
The application forces act on the brake disk via both brake linings. Since, in terms of construction, the linings are designed as wearing parts, they are generally softer than the brake disk, i.e., the linings undergo a change in the thickness of the lining over their time in use: they wear. The brake disk can also wear. This wear gives rise to the need for wear adjustment to compensate the change due to wear, thus establishing a constant release clearance. A constant release clearance is required to keep the response times of the brake short, to ensure the freedom of movement of the brake disk and to maintain a reserve stroke for limiting load cases.
An example of a wear adjustment device is described by document DE 10 2004 037 771 A1. In this case, a driving rotary motion, e.g., that of a torque limiting device, having a ball ramp, for example, is transmitted to an adjusting spindle of a pressure plunger via a continuously acting clutch (slipping clutch). In this case, the release clearance is adjusted continuously.
In the case of mechanical adjusting devices, a speed of adjustment is dependent on the transmission ratio of the adjuster drive. For reasons of installation space, however, a large transmission ratio is not always possible.
There is a continuous need in vehicle engineering to save weight and costs, e.g., during assembly and maintenance, while, at the same time, there should be a saving of energy, i.e., fuel.
It is the object of the present invention to provide an improved adjusting device.
It is a further object to provide an improved disk brake.
Yet another object is to indicate a method for operating a wear adjustment device for a disk brake.
An adjusting device is provided which offers a compact construction radially around a threaded plunger. Virtually all its functional components surround the threaded plunger at least partially. It is easier to replace the adjusting device during maintenance and repair than in the prior art.
An adjusting device according to the invention for friction surface wear adjustment on the brake linings and brake disk of a brake, especially for a motor vehicle, having an application device, preferably a pivoted brake lever, where the adjusting device can be coupled to the application device, preferably the pivoted brake lever, on the drive side, and to a spindle unit of the disk brake on the output side, includes a) a drive element, on each side of which a respective rolling element assembly is axially arranged, one of which is designed as a rolling bearing and the other as a ball ramp clutch with a freewheel; b) a pressure element, which is coupled to the ball ramp clutch and forms an overload clutch together with a portion of the ball ramp clutch; c) an output element, which is coupled to the pressure element, for coupling to a coupling wheel, which is designed for coupling to the spindle unit; d) an energy storage element for generating a preloading force of the ball ramp clutch and of the overload clutch; and e) a support body, one end of which is connected to a bearing plate and around which the drive element, the rolling element assemblies, the overload clutch, the output element and the energy storage element are arranged axially in series with the bearing plate, wherein the energy storage element is arranged between a supporting portion of the support body and the pressure element.
A space-saving, compact and easily replaceable adjusting device is obtained.
A disk brake according to the invention, preferably air-operated, in particular for a motor vehicle, having an application device, preferably a pivoted brake lever, at least one spindle unit, each having a threaded plunger, and at least one wear adjustment device, which is coupled to the application device, preferably the pivoted brake lever, is configured in such a way that the wear adjustment device has the adjusting device explained above.
In one embodiment, the support body is in the form of a sleeve, where the interior of the support body is designed to receive a threaded plunger of a spindle unit of the disk brake to be assigned thereto. The sleeve design results in a saving of weight and materials and furthermore results in the possibility of mounting the adjusting device on the threaded spindle.
The support body has a bearing portion and a receiving portion, which are connected by a shoulder, where the bearing portion has a smaller outside diameter than the receiving portion. This makes it possible to obtain a very largely uniform outside diameter of the adjusting device without major deviations.
In another embodiment, another end of the receiving portion is designed as a supporting portion for the energy storage element. By virtue of the sleeve design, a simple production process for the support body can be designed, and the supporting portion can also be produced in one production cycle.
The output element is also in the form of a sleeve with two cylindrical portions, which can likewise be produced easily by forming without additional machining. Moreover, the two cylindrical portions of the output element have different diameters and are connected by a shoulder portion, where one cylindrical portion, as an output coupling portion, has a larger diameter than the other cylindrical portion, which is designed as an output portion for coupling to the coupling wheel. The energy storage element is arranged between the output coupling portion of the output element and the support body. At the same time, the design of the output element allows coverage and protection from contaminants.
In yet another embodiment, the output portion of the output element extends into an interior space of the coupling wheel and interacts with an internal profile of the coupling wheel via transmission elements, preferably balls. In this way, easy insertion into and removal from the coupling wheel for assembly, maintenance and replacement can be performed quickly. Since, as a further development, the coupling wheel can also simultaneously include the function of a synchronizing wheel of a synchronizing device, no disassembly of the synchronizing device is required for assembly, maintenance and replacement work, and this saves time and costs. Decoupling of the adjusting device from the synchronizing device is thereby achieved.
In another embodiment, the output portion of the output element, the internal profile of the coupling wheel and the transmission elements form a Cardan joint. This results in the advantage that pivoting and vertical movements of a crossmember into which the threaded plungers are screwed can thereby be compensated.
As a yet further development, the coupling wheel is furthermore provided with an engagement portion, which is provided for interaction, for conjoint rotation, with a threaded plunger of a spindle unit of the disk brake to be assigned thereto. The engagement portion can have dogs which interact with axial grooves in the associated threaded plunger, for example. This allows not only simplicity of assembly and disassembly but also relative axial mobility between the coupling wheel and the threaded plunger.
If, in another embodiment, the coupling wheel has a synchronizing portion, which is provided for coupling to a synchronizing means of a synchronizing device of the disk brake to be assigned thereto, there is the resulting advantage of wide functionality of the coupling wheel. The synchronizing portion can be sprocket teeth and the synchronizing means can be a chain, for example.
In another embodiment, the drive element has a contoured portion, which is designed to interact with an actuating contour of an actuator of the application device, preferably of a pivoted brake lever of the disk brake to be assigned thereto. For example, the contoured portion can be teeth, which are formed peripherally, thus making possible easy alignment between the actuator and the drive element.
As a further embodiment, a ramp ring of the ball ramp clutch and the drive element are coupled by an elastic coupling element 14, e.g., a torsion spring. In this way, the ramp balls can be in a particular position or placed in such a position in the ball ramps of the ball ramp clutch. Moreover, a reduction in the backlash of the freewheel can thus be made possible.
In one embodiment of the disk brake according to the invention, the adjusting device of the wear adjustment device is mounted on the threaded plunger of the at least one spindle unit of the disk brake and at least partially surrounds the threaded plunger. When the brake linings are new, the adjusting device surrounds the threaded plunger over at least two thirds of the axial length of the threaded plunger. One advantage here is that a compact construction is made possible.
A disk brake furthermore has at least two spindle units, each having a threaded plunger, where the threaded plungers are screwed into a crossmember, where the crossmember interacts with the application device, preferably the pivoted brake lever, and a synchronizing device. The wear adjustment device furthermore has a driver unit, which is coupled to the threaded spindle of the other spindle unit of the two spindle units of the disk brake.
In one embodiment, the synchronizing device is arranged on the crossmember. The synchronizing device, which is thus situated within the caliper housing, can lead to a shortened construction of the brake caliper. Moreover, no cover is required for the synchronizing device. As a result, covers with a radial sealing concept can be used for both openings in the brake caliper housing which are used for the adjusting device and the driver device, and this simplifies sealing.
Moreover, the elimination of a cover for the synchronizing device opens up more possibilities of variation for the cylinder flange of a pneumatic cylinder.
In yet another embodiment, the synchronizing device has coupling wheels, each of which is coupled for conjoint rotation to the respective threaded plunger of one of the at least two spindle units, and has a synchronizing means, wherein each coupling wheel has a synchronizing portion for interaction with the synchronizing means. In this case, the synchronizing means can be a traction means. For example, the synchronizing means in the form of a traction means can be a chain, wherein the synchronizing portions of the coupling wheels are chain sprocket teeth.
Moreover, provision is made for the coupling wheels of the synchronizing device to be arranged in a fixed location and rotatably on the crossmember. This results in a compact construction.
In another embodiment, the crossmember, together with the threaded plungers and the synchronizing device, is embodied as a preassembled functional unit. In this way, a modularized assembly concept is enabled. Moreover, the crossmember can be exchanged as a pre-synchronized unit together with the threaded plungers during maintenance or servicing without an increased risk as regards incorrect assembly (e.g., unsynchronized threaded plungers).
In yet another embodiment, the threaded plungers of the spindle units are of the same design and construction. It is thereby possible to simplify manufacture.
In another embodiment, the coupling wheel of the spindle unit is coupled to the driver unit by one end of an attachment, which surrounds the associated threaded plunger partially in the manner of a sleeve, where another end of the attachment has an actuating end for manual actuation. A compact construction is thereby achieved.
In yet another embodiment, a reaction-side brake lining is of larger design than an application-side brake lining. By the enlarged surface, the thickness of the friction material of the brake lining can be reduced while keeping the wear volume the same. This results in greater rigidity of the entire disk brake and a reduced capacity of the adjusting device. This reduced capacity furthermore leads to installation space advantages through shorter threaded plungers.
A method for operating a wear adjustment device of a disk brake, in particular the disk brake described above, includes the following. (S1) Determination of parameters, by which it is possible to infer the current wear of brake linings and of an associated brake disk, during a braking operation, and estimation of wear of the brake linings and of the brake disk by the determined parameters during the braking operation; (S2) comparison of the wear estimated in this way with a reference value and specification of a number of brake actuations if the reference value is reached or exceeded; and (S3) actuation of the disk brake in accordance with the specified number of brake actuations in order to operate the wear adjustment device with a high speed of adjustment.
As a result, a setpoint release clearance of the disk brake is reached rapidly since a reduction in release clearance can be achieved in a shorter time. Moreover, energy, e.g., compressed air, required to actuate the brake when the release clearance is too large, to overcome the excessive release clearance, is saved. This energy saving leads to lower fuel consumption.
In another embodiment, an application force is chosen for the disk brake in (S3) in such a way that the response force for the disk brake is just reached. This allows an adjusting operation without the occurrence of a braking effect.
In yet another embodiment, (S3) is carried out as soon as the disk brake is released during the braking operation in which (S1) has been carried out. A speed of adjustment is thereby further increased.
A maximum braking performance is thus obtained, even after high loading of the disk brake.
Short response times of the brake are furthermore made possible.
When braking an axle, there is a reduction in the braking torque deviation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.